to average :l
  output quotient apply "sum :l count :l
end

to make.sma :name :period
  localmake "qn word :name ".queue
  make :qn []
  define :name `[ [n]              ; parameter list
    [if equal? count :,:qn ,:period [ignore dequeue ",:qn]]
    [queue ",:qn :n]
    [output average :,:qn]
  ]
end

make.sma "avg3 3

show map "avg3 [1 2 3 4 5]     ; [1 1.5 2 3 4]

show text "avg3     ; examine what substitutions took place
[[n] [if equal? count :avg3.queue 3 [ignore dequeue "avg3.queue]] [queue "avg3.queue :n] [output average :avg3.queue]]

; the internal queue is in the global namespace, easy to inspect
show :avg3.queue    ; [3 4 5]